I need to buy some non-standard size u-bolts. Do you have any guidelines that will help me with ordering the u-bolts I need from Portland Bolt?
Portland Bolt can manufacture custom u-bolts that are made from 1/2” diameter and larger steel. So as long as the u-bolts you need are 1/2” in diameter or larger, we can most likely manufacture them, within the capabilities of our bending equipment and the limitations of the steel itself. To better understand what can be manufactured you will need to know a little about the way that we manufacture u-bolts.
Round Bend U-Bolts
There are two types of u-bolts, round bend u-bolts and square bend u-bolts. Round bend u-bolts are shaped like the letter “U” and are typically used to attach something to a round pole or a pipe. To manufacture a round bend u-bolt, we first cut a section of steel round bar to the appropriate length and then bend that piece of steel around a pin that has the same diameter as what is desired in the final u-bolt. For example, if you need a round bend u-bolt that will fit around a 3” diameter pole, we would bend it around a 3” diameter pin. You can see a brief video of this operation below:
Square Bend U-Bolts
The other type of u-bolt is a square bend u-bolt. Applications can vary, but this style of u-bolt is usually going around something generally square or rectangular in shape, such as a square wooden beam or square steel tubing. Fabricating this style of u-bolt is more complicated and requires some additional considerations. Before we can begin manufacturing this style of u-bolt we will need to know some additional information. Because the u-bolt will be manufactured from steel bars that are round in shape, and will be bent around a round pin, the bends themselves will have a rounded profile. In many construction applications this is not a problem. In some precision applications, however, such as in some automotive or trailer uses, the u-bolt may be required to have a true, sharp, right angle inside the bend. In cases like these, we would most likely not be able to manufacture the u-bolt required.
Determining A Bend Radius
Once you have determined that bends with a radius will be acceptable for your application, the next thing that must be considered is the relationship between the diameter of the u-bolt and the radius of the bend. For a square bend u-bolt the general rule of thumb is that the radius of the bend must be at least twice the diameter of the material being bent. For example, in the case of a square bend u-bolt being made from 1/2” material, the radius of each bend must be at least 1”. In some cases, sharper bends can be performed through a hot bending operation which involves additional labor.
Another aspect of u-bolt manufacturing that must be considered is the amount of thread on each leg in relation to the length of those legs. The thread length will be a function of the diameter of the material, the type of steel being used (mild steel or high strength), and the radius of the bend. Generally speaking, u-bolts fall into two categories here:
- U-bolts made from mild steel that is 1″ diameter or smaller, OR
- U-bolts made from either mild steel 1-1/8″ diameter and above, or made from high strength steel of any diameter.
In the case of group 1 the general rule is that the threads should not begin until you are at least one inch beyond the radius of the bend. In the case of group 2, the rule is that the threads should not begin until you are at least 1″ beyond the diameter (twice the radius) of the bend. The reason for these restrictions is because threads extending further down the leg of the u-bolt will encroach into the area of the steel being bent during fabrication, and will subsequently be smashed flat by the bending rollers. Bear in mind that the 1″ distance beyond the radius or diameter is the minimum. More distance is always preferable.
A final item that may sometimes be a factor to consider is the ASTM specification to which the u-bolts you need are being manufactured. If your u-bolts are being manufactured from a quenched and tempered, high-strength steel there is a possibility that the material may have to be heated before bending to achieve the desired shape. In cases like this, the material will have to be sent to a metal heat treating company to undergo a heat treating process to restore the high strength properties in the portion of steel that was heated during fabrication. This will add additional time and cost to the production of your order.
We Can Help
Keep in mind that the information in this FAQ is intended to serve as a guide to help you better understand the types of u-bolts that we can best help you out with. As with any guidelines, there will always be special cases and exceptions to the rules. If you are uncertain about whether Portland Bolt can help you out with your u-bolt requirements, please contact one of our experienced sales team members and we will be glad to help walk you through it!